The major goal of the Neuropathology (NP) core of the Rush ADC is to provide investigators with well preserved brain tissue and complete diagnostic neuropathological evaluations from clinically well-characterized study participants. Provision of such tissue is necessary in order to fulfill the overall goal of the ADC to promote scientific investigations of Alzheimer's disease (AD). The specific aims of the NP Core are to: 1. Obtain brain tissue from clinically well-characterized elderly individuals with Alzheimer's disease, corresponding closely-matched control patients, and other neurological disease control cases through close collaboration with the Clinical and Religious Orders Study Cores; 2. Obtain the brain tissue with minimal postmortem intervals, preserved and processed in a standard and uniform fashion so that it can be used in various experimental protocols by a variety of investigators; 3. Perform a thorough and detailed neuropathological evaluation using standard, up-to-date, consistent diagnostic criteria for AD, Parkinson's disease (PD) and related disorders; 4. Reliably store and index the tissue and data, allowing for accurate and rapid information retrieval and tissue distribution to investigators. The ROS core is the source of clinical and pathological data and brain specimens which are especially valuable to investigators. It is composed of elderly Catholic clergy who volunteer to be neurologically and neuropsychologically examined each year, and consent to brain autopsy upon their death. The NP core has received, processed, preserved, and evaluated 130 brain autopsies from the subjects of the ROS core. Clinically, the group is composed of 37% with no cognitive impairment, 21% with mild cognitive impairment, and 42% with dementia. The NP core finds this brain tissue to be an extremely important resource for studies of both AD and aging-associated changes in the brain, as well as their inter-relationship.